Analog Devices VISUALDSP++ 3.5, Manual, Page: 26 / 166

Booting Modes
1-6 Vi+ 3.5 Loader Manual
for 16-Bit Processors
PROM Booting Mode
After reset, the processor starts reading data from any parallel or serial
PROM device. The PROM stores a formatted boot stream rather than raw
instruction code. Beside application data, the boot stream contains addi-
tional data, such as destination addresses and word counts. A small
program called kernel or loader kernel (described
on page 1-7 ) parses the
boot stream and initializes memories accordingly. The loader kernel runs
on the target processors. Depending on the architecture, the loader kernel
may execute from on-chip boot ROM or may be pre-loaded from the
PROM device into on-chip SRAM and execute from there.
The loader utility generates the boot stream from the linker’s executable
file and stores it to file format that can be burned into the PROM.
Host Booting Mode
In this scheme, the target processor is slave to a host system. After reset,
the processor delays program execution until it gets signalled by the host
system that the boot process has completed. Depending on hardware capa-
bilities, there are two different methods of host booting. In the first case,
the host system has full control over all target memories. It halts the target
while it is initializing all memories as required. In the second case, the
host communicates by a certain handshake with the loader kernel running
on the target processor. This kernel may execute from on-chip ROM or
may be pre-loaded by the host devices into the target’s SRAM by any
boot-strapping scheme.
The loader/splitter utility generates a file that can be consumed by the
host device. It depends on the intelligence of the host device and on the
target architecture whether the host expects raw application data or a for-
matted boot stream.